Electric resistance welded steel pipe having identifiable seam portion and method for manufacturing the same
US10369655B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 2016 |
| Grant date | Aug 6, 2019 |
| Priority date | — |
| Expiry date | May 18, 2036 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C22/12
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
An electric resistance welded steel pipe having an identifiable seam portion and a method for manufacturing the same. The electric resistance welded steel pipe includes a steel pipe portion with a seam portion, which is formed by electric resistance welding, and a coating portion of zinc phosphate. The coating portion covers at least an outer surface side of the steel pipe portion. A part of the coating portion that is immediately above the seam portion forms a color difference portion that has a width W along a pipe circumferential direction of greater than or equal to 0.1 times a wall thickness of the pipe and less than or equal to the wall thickness of the pipe. The color difference portion has a visually identifiable color difference from the other parts of the coating portion.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.